Quinoline compounds



Patented Apr. 8, 1941 QUINOLINE COMPOUNDS James R. Bailey assignors toUnion Los Angcles, Calii'.,

and Carrol L. Key,

Oil Company of California, a corporation of California Austin, Tex.,

No Drawing. Application August 27, 1937, Serial No. 161,278

6 Claims.

This invention relates to a composition of matter and the method ofproducing the same. More specifically the invention relates to theproduction of 2,3-dimethyl-8-ethylquinoline and the method of producingthis alkylated quinoline.

We have discovered a method whereby 2,3- dimethyl-B-ethylquinoline maybe directly synthesized. Furthermore, we have discovered that2,3-dimethyl-8-ethylquinoline is present in certain fractions of certainpetroleum oils, shale oils, and oils obtained by Dyrolitic decompositionof protein matter such as cotton seed meal and may be recoveredtherefrom by my process. Furthermore we have discovered a method whereby3-methyl-8-ethylquinoline may be synthesized.

We have discovered that 2..3-dimethyl-8-ethylquinoline is a constituentof certain petroleum oil. More specifically, we have discovered thatnitrogen base mixtures recovered from the kerosene cut of Californiaasphalt base crude contain an appreciable quantity of2,3-dimethyl-8-ethylquinoline. The specific petroleum fraction which weuse to recover this nitrogen. base is, as explained above, a crudekerosene distillate obtained from California asphalt base crude oil byfractional distillation. We prefer to first concentrate the nitrogenbases by extraction of such a distillate with a selective solvent. In aparticular instance kerosene distillate was extracted with sulphurdioxide, as in the well known Edeleanu refining process. and an extractwas obtained which comprises the bulk of the nitrogen bases present inthe kerosene distillate, as well as the usual extract constituents suchas aromatic and naphthenic hydrocarbons. The extract thus obtainedcomprising the nitrogen bases and various hydrocarbons had a boilingpoint range of 430-520 F. and a pressure of 64-85 mm. of mercury; aspecific gravity at 60 F. of 0.995; an A. P. I. gravity at 60 F. of10.7; a Savbolt Universal viscosity of 60 seconds at 100 F.; a sulphurcontent of 0.36% by weight; a nitrogen content of 4.62% by weight; andan alkalinity, calculated as NaOH of 18.5% by weight.

The above extract was then treated in the following manner for therecovery of the nitrogen bases contained therein.

To a barrel of the extract was added 19 gallons of 20% sulphuric acidand the mixture was agitated with air for six hours. The mixture wasthen allowed to stand for several hours to effect stratification. Thehydrocarbon oil layer was removed and discarded and the aqueous acidlayer was then treated with caustic alkali to ef-' feet liberation ofthe nitrogen bases, as on oily phase insoluble in the water.

After removal of the water this mixture of bases was then treated in thefollowing manner for the recovery of its content of the2,3-dimethyl-8-ethylquinoline:

This mixture of bases was charged to a 10 gallon iron still andfractionally distilled under reduced pressure to obtain cuts of 500 cc.volume. These cuts were recombined and redistilled. from a 5 liter Pyrexglass still to cuts of cc. each. After five distillations the cutsboiling from 283- 287 C. were combined to form 5700 cc. of distillatewhich served as the material from which the new base was isolated.

These combined cuts were brought into solution in strong hydrochloricacid which has been diluted with an equal volume of water and thisaqueous solution was then extracted with a volume of chloroform equal tothe original volume of the bases. By this method non-aromatic basehydrochlorides are substantially all extracted by the chloroform, whilethe aromatic base hydrochlorides remain in the aqueous phase. From theextracted aqueous solution 1500 cc. of arcmatic bases were recoveredwith a boiling point of 284 C. and a refractive index, n 25/D of 1.5812.These aromatic bases were then fractionally distilled in a Pyrex stilland a cut was made of the condensate boiling between 282 C. and 287 C.This cut was then subjected to an amplified distillation in which thebases were dissolved in' 12 volumes of hydrocarbon oil of a boilingrange of 260-290 C. prior to the distillation. The cuts taken from282-285" C. during this amplified distillation were found to containalmost pure 2,3-dimethyl-8-ethylquinoline, in admixture withhydrocarbons from the diluent oil. This base was then separated fromthese cuts by extraction with aqueous sulphurous acid and treatment ofthe aqueous extract with caustic alkali. Final purification was effectedby crystallization of the pic-rate and liberation of the base from thepicrate with caustic alkali.

In another instance we omitted the step of amplified distillation, i. e.we carried out the final distillation in the absence of any addedhydrocarbon oil, and from the cuts boiling in the neighborhood of 284 C.we obtained substantially the same yield of2,3-dimethyl-8-ethylqulnoline.

The base recovered in the above manner and which has the structure2,3-dimethyl-8-ethylquinoline was identified as follows:

Analysis calculated for C1aH15N: C, 84.32; H, 8.10; N, 7.57. Found:. C,83.94; H, 7.89; N, 7.54.

Calculated molecular weight. for CraHmN:

2 Molecular weight: substance, 15.50 mg.; camphor 155.55 mg.; freezingpoint depression, 21 18 Found: molecular weight 189.

Physical characteristics: boiling point 284.6" C.; n 20/D 1.5940, D.20/41.017.

Picrate-Thls salt, which is dlfllcultly soluble in the common solvents,crystallizes from glacial acetic acid in slender yellow needles meltingat 220 C.

Knalysis calculated for CieH1aO1N4: C, 55.07; H, 4.35; N, 13.53. Found:C, 55.19; H, 4.34; N, 13.46.

Nitrate.-This salt crystallizes from alcohol or water in fine needlesmelting at 166 C. and decomposing just above this temperature.

Analysis calculated for CnHreOaNa: C, 62.90; H, 6.45; N, 11.29. Found:C, 63.19; H, 6.39; N, 11.30.

Hydrochloride.-On dissolving the base in a slight excess of concentratedhydrochloric acid, the hydrochloride separates and can be recrystallizedfrom alcohol or water in long slender .needies melting at 212-2l4 C.with decomposition.

Analysis calculated for C13H15N.HC12 C, 70.40; H, 7.22; N, 6.32; Cl,16.02. Found: C, 70.43; H, 7.24; N, 6.33; Cl, 16.06.

Acid sulphate.-This salt, prepared by adding a slight excess ofconcentrated sulphuric acid to an acetone solution of the base,crystallizes from alcohol in fine needles melting at 239-240 C.undecomposed.

Analysis calculated for CiaHi5N.H2SO42 Found: N, 4.98.

Mercuric chloride salt.-Mercuric chloride (one mole) added to the base(one mole) in dilute hydrochloric acid solution precipitates the doublesalt. It crystallizes from water in large needles and from alcohol inmicroscopic needles melting at 212-214 C. undecornposed.

Analysis calculated for CmHmNCHLHgCh: N, 2.84; Found: N, 2.88.

C'hromata-On addition of potassium chromate to the hydrochloride inweal: acid solution, the chromate separates in a gelatinous form whichon standing becomes crystalline. It crystallizes from 50% glacial aceticacid in microscopic rhombic prisms which decompose around 100 C.

Analysis calculated for C13H1sN.HzCIO4Z N, 4.62; Found: N, 4.61.

2,3-dimethyl quinoiine-$-carhoscylic acidM-A mixture of 6 grams ofchromic anhydride and 78 cc. of 1:5 sulphuric acid is refluxed for 60hours with about 10 grams or" the base. The solution, afterneutralization with ammonium hydroxide to where precipitation of chromichydroxide begins, is extrac ed with chloroform in a yield oi about 19%.For purification, the reaction prodnot is decolorized in acueoussolution with filtchar. followed by recrystallization from alcohol andwater in long needles melting at 202 C. A mixed melting point with aknown sample of 2,3- dimethyl quinoline-s-carboxylic acid showed no deression.

Analysis calculated for Cmi-l'nOaN: C, 71.64: H, 5.47: N. 6.97. Found:C, 71.64; H, 5.46; N, 6.87.

2.3-dimethyl auinoZz'ne.-'I'he above acid was decarboxylated bydistillation with soda-lime and the resulting base was dissolved inether and precioitated with an alcoholic solution of plcric acid. Thepicrate recrystallizes from glacial acetic acid in microscopic hexagonalprisms melting at 231 C. This product, mixed with a known sample of2,3-dimethyl quinoline plcrate' showed no depression in melting point.

3 methyl 8-ethyl-Z-dimethylolmethulquinoline.-In conformity with theprocedure or Keenigs and Stockhausen (W. Koenlgs and F. Stockhausen,Ber. 84, 4331 (1901) 5 g. of dimethylethylqulnoline and 25 ml. offormalin in a sealed tube are heated on a steam cone for 45 hours. Thereaction mixture, processed in the usual way, yields the dimethylolcompound which, after recrystallization from chloroform and ethylacetate, melts at 94-95 0.

Analysis calculated for CitHnOzNZ C, 73.47; H, 7.75; N, 5.71. Found: C,73.31; H, 7.69; N, 5.91.

Picrate.-This salt precipitates on the addition of an alcoholic solutionof picric acid to the dimethylol base in ether and can b recrystallizedfrom water or alcohol in long slender needles melting at 165.5 0.

Analysis calculated for Carl-1:20am: C, 53.16; H, 4.64; N, 11.81. Found:C, 53.47; H, 4.80; N, 11.88.

3 methyl 8 ethylquinoline.The dimethylol compound (5 g.) in 250 ml. of1:1 nitric acid is boiled for 6 hours. On evaporation of the solution, apractically quantitative yield of 3-methyl- B-ethylquinoline2-carboxylic acid melting at 84- C. results. Since a well knownprocedure is involved here for conversion of a methyl at position 2 tocarboxyl in quinoline homologs, this product was not analyzed. Afterdecarboxylation at a temperatur of 180 C., the resulting base ispurified through recrystallization of its picrate (A) from benzene andglacial acetic acid. The assigned structure, B-methyl-S-ethylquinoline,was confirmed by synthesis. (Cf. Carl Beyer, J. prakt. Chem. 33, 419(1886) von Miller and Klnkelin, Ber. 20, 1916 (1887).)

Synthesis of 3-methyl-8-eihylquinoline.--Dry hydrogen chloride isintroduced at a moderate rate into a mixture of propionic aldehyde (5g.) and methylal (6 g.) for 5 minutes. On the addition of o-ethylaniline(1.8 g.) in concentrated hydrochloric acid (5 g), a reaction begins andis completed by boiling the solution for 3 hours. An equal volume ofwater is added, the filtered solution is treated with a slight excess ofsodium nitrite, and after concentration to a small volume,

the bases are liberated with sodium hydroxide and extracted with ether.Final purification of the methylethylquinoline, aiter fractionaldistillation at diminished pressure, is effected through the picrate.(B) The identity of salts A and B was confirmed by a mixed melting pointdetermination. The new base which was obtained in a yield of 8% has arefractive index 71. 25/13, of 1.5946.

Picrate A.-Ana.lysis calculated for GlBIIIGOINl lI C, 54.00; H, 4.00; N,14.00. Found: C, 53.84; H, 4.07; N, 14.02.

Piorate B.--Found: C, 54.01; H, 4.00; N, 14.03.

Synthesis of 2,3-dz'methyl-B-ethylquinoline.- Final confirmation of thestructure of the original kerosene base was effected through itssynthesis (Ci'. Doebner and von Miller, Ber. 16, 2464 (1883)), which canbe carried out as follows: a mixture of tiglic aldehyde (1 mole) and o-ethylaniline (4 moles) is heated open to the air for 4 hours on a waterbath and then steam distilled. The solution, after liberation of thebases with sodium hydroxide, is again steam distilled and thedistillate, acidified with hydrochloric acid, is treated at roomtemperature with sodium nitrite. Following the removal of thesupernatant oil by other extraction, the solution is boiled, fil-=tered, made alkaline with sodium hydroxide, steam distilled and againextracted with ether. The base, regained from the solvent, gave apicrate which, admixed with the kerosene base picrate, produced nodepression of the melting point (220 (3.).

Analysis calculated for Ci9H1aO7N42 C, 55.07; H, 4.27; N, 13.53. Found:C, 55.19; H, 4.34; N, 13.46.

It is to be understood that the disclosures here made are to beconsidered as illustrativeand not as limiting except as required by thestate of the prior art.

We claim:

1. 2,3-dimethyl-S-ethylquinoline.

2. 2,3-dimethyl-8-ethylquinoline with a boiling point oi. 284.6 C.

3. A process for the recovery of 2,3-dimethyl-8- ethylquinoline fromasphalt base petroleum which comprises distilling the petroleum toobtain a distillate comprising kerosene, extraction of the saiddistillate with a mineral acid to obtain a mixture of nitrogen bases,separation or this mixture into aromatic and non-aromatic portions, andfractionally distilling the aromatic portion to obtain outs boilingwithin 2 of 284 C. at atmospheric pressure and which consistssubstantially of 2,3-

dimethyL-8-ethylquinoline 4. A process as in claim 3, plus a furtherpurification step of fractional crystallization of a salt of the crude2,3-dimethyl 8-ethylquinoline.

5. A process as in claim 3, in which the aromatic bases are separatedfrom the non-aromatic bases by extraction of an aqueous HCl solution ofthe mixed bases with chloroform.

6. A process as in claim 3, in which at least a part of fractionaldistillation of the aromatic bases is made in the presence 01' a diluenthydrocarbon oil with a distillation range comprehending the distillationrange of the aromatic bases.

JAMES R. BAILEY. CARROLL. KEY. v

